Hi.
New here so just want to introduce myself before I ask for advice. My name is Lee and I live in Australia. Mainly a collector and tinkerer. Not really musical but that doesnt stop me having fun!. Ive gone back to my youth and re-discovered analog warmth.
Anyway, recently purchased mint condition MG-1 from good old Ebay for equivalent of around $320US. thought that was an ok price, though certainly not a bargain!, if everything was perfect.
For the first few hours of intermittant playing everything was sweet. Had the Moog bass going in no time. Then last night, I had it on for about 1hr when I went to play it and it was like the envelope was being trigered, fast on the upper part of the keyboard, slower on the lower part. I played around and found the polyphonic section was several octaves lower and out of tune, and when the pitch got to a particular low level, it would begin triggering the oscillators, even when the poly section is mixed at a 0 level. I found by turning the tuning pot as sharp as possible, it delays the problem a little. With the keyboard off for a while then turned on with only the poly sectioned turned up, it starts at the right pitch and drops on octave in about 15 seconds, its a smooth drop, like a slow portamento. within 30 secs its 3 octaves or so down, and by then its beginning to trigger the oscillators, if I mix them in. After being on for about 10 minutes, even with the poly sectioned tunes as sharp as possible, its beginning to encroach on the bottom few keys, and I fear it will only get worse.
Hope that makes sense, I am desperate as I pushed the budget to afford it, and was hoping for more than 4 hours use!. I am comfortable with a soldering iron and also spent the morning cleaning the remains of the dust protection, hoping that I might discover something that is causing my problem
I guess to summerize above, what is it that keeps the poly section, or any sound source for that matter, at its correct pitch?. Is it perhaps a capacitor not working correctly. I am having trouble getting any local tech’s here to look at it, as they all seem scared!!.
I guess I might just start randomly replacing capacitors, then perhaps resistors.
If I turn on the keyboard, with my key on the top note, it starts at the right pitch and sropd immediately in an even portamento fashion till eventually it is so low it’s inaudible. its only the Poly section, the basic square wave
I wouldn’t start randomly replacing components. Unless you are certain that a cap is bad, or a resistor fried, a random approach could end up making the problem worse instead of better.
Try contacting Kevin Lightner first. He might be able to help directly or point you to a better source of assistance.
Hi Lee,
I have the MG-1 too. After reading your posts I’m still a little confused as to what the problem is. From what I understand, it’s having some tuning/drifting issues? Let me point out that the poly section is unaffected by tone 1 and 2’s octave selectors. The poly sound just stays in that one range, so maybe you had the octaves on your tone 1 and 2 set really high, which when mixed with the poly sound would be a few octaves apart? I’m sure you know that the poly section tunes seperately from the other 2 oscillators… so if you’re mixing them together, you’ve got to fine tune them. My only thought for the pitch gliding up and down slowly would be if you had the “tone source” slider up (even a little) on the modulation section… with the rate set to slow.
These may be silly suggestions, but you said you weren’t very musical, so if you’re new to moog’s they can seem broken if you don’t really know your way around waveshaping etc. I know it took me quite a while to make a pleasant tone when i first bought my opus 3. Having the poly section drop like portmento is definately weird though.
HI Jim,
thanks for that. It is hard to get a clear picture of the problem out of my head and onto paper!.
Basically, I have done a fair amount pf synth programming and im confortable with the technical aspect. Ive owned several other analog keyboards, so understand the basics. Just cant play them too well!..
The oscillators work perfectly. The onlt problems is the poly section wont hold its correct pitch. You allow for a little drift with the VC0 stuff, but the poly section drops from a normal note to so low that it becomes inaudible, due to the low pitch. Ive checked the basics like modulation and glide. When the pitch of the poly section gets to an extremely low level, thats when the oscillators become affected.
Everything else works perfectly, and the poly section was fine.
Ive got a few contacts so will persist. Thanks again for your help. Its worth persisting, such a great little keyboard!
